Fracture dislocation of the Proximal Interphalangeal Joint (PIP) is a common injury of the digits of the hand. The principle of traction to treat a fracture is a relatively old idea, but the concept of movement is relatively new. In 1978, Oganesyan described an apparatus for the treatment of intra-articular fractures, with simultaneous movement, see U.S. Pat. No. 4,100,919. The device was constructed of at least two wires drawn through bones on either side of the affected joint. These wires were rigidly connected to arches, which externally bridge the affected bones, creating a rigid construct. A key feature of this device was a threaded rod designed to alter the distance between the wires, and the bone segments attached thereto. The purpose of the distraction was to increase the distance between the bones at the axis or rotation of the joint, in order to promote healing and preserve the cartilage at the joint during active motion. The traction applied to the articulation not only aimed to re-focus the skeleton but also to generate a force of distal distraction. This distraction offers several beneficial effects. First, it allows the reduction of articular fragments and restoration of continuity by drawing on their joint ligament attachments and the volar plate, via the process of ligamentotaxis. Maintaining this tension allows distal fragments to remain in place during healing. Secondly, the distraction force prevents retraction of distal capsulolabral structures. Further, joint mobilization improves cartilage regeneration and healing. The combined results of these two methods are anatomic restoration of joint function, all without invasive surgery.
Then in 1986, Schenck introduced this technique to the field of hand surgery, see U.S. Pat. No. 4,724,827. Schenk described an apparatus to treat fracture luxations of the PIP with dynamic traction. His device involved passage of a K-wire transversely through the phalanges distal to P2, and attaching elastic bands to a rigid arc surrounding the digit. The elastic bands created a stretching force of 300 grams, and the device permitted passive motion of the digit. Patients treated with this device responded well to the treatment with little loss of range of motion and none of the complications related to the open reduction procedures, which had been the standard of care up until this innovation. However, the device was cumbersome and complicated and as such it was not well accepted in the surgical community.
In 1986, De Bastiani described a unilateral articulated mini fixation device, see U.S. Pat. No. 4,604,997, which was comprised of a hinge between two blocks, which may be attached to bone segments proximal and distal to the PIP. A threaded adjustment rod is included to provide longitudinal displacement between the blocks.
Then in 1987, Agee described a device for the treatment of unstable fracture luxations of the PIP, see U.S. Pat. No. 4,548,199. The Agee device was based upon placement of two K-wires placed proximal and distal to the PIP. A bone screw was drilled into the ulnar surface of the middle phalanx distal to the PIP, and attached to elastic bands stretched across vertical risers on the K-wire, on either side of the digit, proximal to the PIP. The device provided some degree of distraction of the PIP. It also permitted limited passive and active mobilization of the digit. However, the device was not well tolerated by patients due to its cumbersome design. In addition, the bone screw through the ulnar surface of the phalanges could result in damage to the extensor tendon. As a consequence, the surgical community did not adopt this technique.
Between 1987 and 1993, surgeon inventors described several other devices in an effort to improve the treatment of fracture luxations of the PIP. Most of these devices were complicated and cumbersome, and none were widely accepted in the surgical community.
In 1994, Hotchkiss described dynamic joint support, see U.S. Pat. No. 5,376,091. The invention provided for proximal and distal support sections and means for rigidly connecting each support section to bone and a pair of hinges connecting each support section to each other. Further, the device provided pivoting at the joint to cause movement of the support section and its corresponding attached bone through the movements of flexion and extension. The hinge was driven in its movement by a threaded worm gear mechanism. The dynamic joint support included a threaded rod distraction mechanism for movement of the bones out of contact in the joint, allowing for an active range of motion at the joint. While providing improved clinical results, the device proved expensive to manufacture and cumbersome to use and was subsequently discontinued.
In 1994, Suzuki described a low profile system, which seemed to solve many of the issues related to previous designs. The Suzuki system involved placement of K-wires, one proximal and one distal to the PIP. Results using the operating room constructed Suzuki technique have proven to be better than previous methods. However, patient outcome varies significantly with surgeon skill and experience. The Suzuki technique has a significant learning curve to master the shape and length of the wires. And, care must be exercised to avoid side loading damage to the bones, while bending the wire. In addition, movement of the proximal wire within the bone during passive and active motion can result in an increase in pin tract infection. Furthermore, the device was limited to 30 degrees of flexion, and distraction force varied greatly depending upon the rubber bands available and the length of the physician created device. This limited range of flexion resulted clinically in an average range of motion of only 74 degrees.
In 1999, Graham described a device for treatment of fracture dislocations of the interphalangeal joints, see U.S. Pat. No. 5,976,125. This apparatus required assembly of a series of components including proximal and distal fixators, proximal and distal guide rods, and adjustable threaded distraction rods. By assembling the fixators contralaterally with their respective guide rods and ipsilaterally with respect to their distraction rods, a rigid rectangular construct is formed, through which K-wires may be drilled proximal and distal to the PIP. Placement of the proximal K-wire at the center of the axis of rotation of the PIP, and perpendicular to the PIP, is critical to the optimal functioning of dynamic distraction. Unfortunately, this is difficult to accomplish while holding the construct over the PIP, and frequently results in an off center, or angled K-wire placement with respect to the plane perpendicular to the longitudinal axis of the PIP. Furthermore, this technique is contrary to the traditional surgical technique of wire placement before attachment of the distraction device. The Graham device can be assembled subsequent to wire placement, however this further complicates the procedure due to the number of setscrews, clips, rods, and stabilizers required for assembly. A further disadvantage of this device is that adjustment of the distraction rods is accomplished with an Allen wrench. This can lead to excess distraction force resulting in stress or failure of the digital ligament. Further, no provision is made to lock the distraction rod in place and prevent it from unwinding once optimum distraction has been achieved. In addition, there is no provision to prevent ulnar or palmar luxation of the phalanges, a frequent complication of distraction devices. Finally, due to its complicated design, the device is expensive to manufacture, and bulky to utilize, therefore it has not achieved wide spread use among hand surgeons.
In 2006, Pélissier of France disclosed a simple, low profile device for ligamentotaxis of the PIP (see EP 1898815). His device consisted of two springs, and two grommets held in place by two longitudinal wires. Each longitudinal wire was placed in the lumen of each spring. Once the K-wires were placed at the axis of rotation of the PIP and a point distal to the PIP, the distal wire is bent at a right angle on either side of the digit, and cut to a length approximately equivalent to half the distance between the proximal and distal wires. The open end of each spring is then slipped over the right angle sections of the distal K-wire, and the proximal wire is passed through the grommet at the opposite end of the spring. The proximal wires may then be bent and capped to retain the springs in place on either side of the affected digit. Distraction is accomplished by clockwise rotation of the springs. While the Pélissier device was an improvement over previous designs, this device has one serious disadvantage; the metal springs are placed on either side of the digit, preventing radiographic confirmation of articular distraction in the lateral view.
The novel device herein presented, addresses the deficiencies identified in the above-recited prior art and provides an improved dynamic external distractor for the treatment of complex fracture luxations of the PIP of the hand. The device provides a simple, low cost solution for the treatment of fracture dislocations of the PIP. Further, the device permits standardization of treatment, by enabling surgeons to determine distraction forces, an important treatment parameter, which heretofore was impossible due to the limitations of the above-described prior art devices. Additionally, standardization will permit better patient outcomes than currently possible with existing systems.
All references cited herein are incorporated herein by reference in their entireties.